SIMBAD references

2013ApJ...769..123W - Astrophys. J., 769, 123 (2013/June-1)

Photometric variability in a warm, strongly magnetic DQ white dwarf, SDSS J103655.39+652252.2.

WILLIAMS K.A., WINGET D.E., MONTGOMERY M.H., DUFOUR P., KEPLER S.O., HERMES J.J., FALCON R.E., WINGET K.I., BOLTE M., RUBIN K.H.R. and LIEBERT J.

Abstract (from CDS):

We present the discovery of photometric variability in the DQ white dwarf SDSS J103655.39+652252.2 (SDSS J1036+6522). Time-series photometry reveals a coherent monoperiodic modulation at a period of 1115.64751(67) s with an amplitude 0.442%±0.024%; no other periodic modulations are observed with amplitudes ≳ 0.13%. The period, amplitude, and phase of this modulation are constant within errors over 16 months. The spectrum of SDSS J1036+6522 shows magnetic splitting of carbon lines, and we use Paschen-Back formalism to develop a grid of model atmospheres for mixed carbon and helium atmospheres. Our models, while reliant on several simplistic assumptions, nevertheless match the major spectral and photometric properties of the star with a self-consistent set of parameters: Teff~ 15, 500 K, log g ~ 9, log (C/He) = -1.0, and a mean magnetic field strength of 3.0±0.2 MG. The temperature and abundances strongly suggest that SDSS J1036+6522 is a transition object between the hot, carbon-dominated DQs and the cool, helium-dominated DQs. The variability of SDSS J1036+6522 has characteristics similar to those of the variable hot carbon-atmosphere white dwarfs (DQVs), however, its temperature is significantly cooler. The pulse profile of SDSS J1036+6522 is nearly sinusoidal, in contrast with the significantly asymmetric pulse shapes of the known magnetic DQVs. If the variability in SDSS J1036+6522 is due to the same mechanism as other DQVs, then the pulse shape is not a definitive diagnostic on the absence of a strong magnetic field in DQVs. It remains unclear whether the root cause of the variability in SDSS J1036+6522 and the other hot DQVs is the same.

Abstract Copyright:

Journal keyword(s): stars: evolution - stars: individual: SDSS J103655.39+652252.2 - stars: magnetic field - stars: oscillations, including pulsations - white dwarfs

CDS comments: SDSS J1402+3818 is not identified.

Simbad objects: 28

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2023.01.27-16:08:45

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